In a centrifugal compressor in, for example, a turbo refrigerator or a turbocharger, an inlet guide vane (hereinafter referred to as an IGV) which has a plurality of blades and performs flow rate adjustment is provided. Specifically, in the IGV, flow rate adjustment is performed by adjusting the degree of opening of an inflow flow path of a working fluid by rotating the blades.
Here, Patent Document 1 discloses a vane drive device which is a drive mechanism of an IGV. The drive device performs the adjustment of the degree of opening by rotationally driving each vane by rotating a driven pinion gear provided at a shaft of each vane, through a bevel gear provided annularly by a main drive pinion gear provided in an electric motor.
Further, in a centrifugal compressor of Patent Document 2, the adjustment of the degree of opening is performed by rotating an annular member provided on a concentric axis with a rotary shaft on the outer periphery side of an inflow nozzle section, through a connecting link, thereby rotationally driving each vane supported on the annular member.